[Federal Register Volume 64, Number 48 (Friday, March 12, 1999)]
[Rules and Regulations]
[Pages 12247-12249]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-5991]



[[Page 12247]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-106-AD; Amendment 39-11071; AD 99-06-07]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-60 and SD3-60 
SHERPA Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Short Brothers Model SD3-60 and SD3-60 SHERPA series 
airplanes, that requires repetitive inspections to detect corrosion 
and/or wear of the top and bottom shear decks of the left and right 
stub wings in the area of the forward pintle pin of the main landing 
gear (MLG), and repair, if necessary. This amendment is prompted by 
issuance of mandatory continuing airworthiness information by a foreign 
civil airworthiness authority. The actions specified by this AD are 
intended to detect and correct corrosion and/or wear of the top and 
bottom shear decks of the left and right stub wings in the area of the 
forward pintle pin of the MLG, which could result in failure of the MLG 
to extend or retract.

DATES: Effective April 16, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 16, 1999.

ADDRESSES: The service information referenced in this AD may be 
obtained from Short Brothers, Airworthiness & Engineering Quality, P. 
O. Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. This 
information may be examined at the Federal Aviation Administration 
(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, 
SW., Renton, Washington; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to all Short Brothers Model SD3-60 
and SD3-60 SHERPA series airplanes was published as a supplemental 
notice of proposed rulemaking (NPRM) in the Federal Register on July 
24, 1998 (63 FR 39769). That action proposed to require repetitive 
inspections to detect corrosion and/or wear of the top and bottom shear 
decks of the left and right stub wings in the area of the forward 
pintle pin of the main landing gear (MLG), and repair, if necessary. 
That action also proposed to expand the applicability to include an 
additional airplane model.

Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter supports the proposed rule.

Remove Repetitive Inspections or Extend Interval

    One commenter, an operator, requests that the repetitive 
inspections of the proposed AD be removed as a requirement when no 
corrosion or wear is found during the initial inspection. The commenter 
states that if no corrosion or wear is found during this initial 
inspection, this would indicate that all surfaces are being adequately 
protected and maintained by the present maintenance program. The 
commenter also notes that repeated removals of parts for the 
inspections will accelerate the wear of the alodine coating, increasing 
the risk of corrosion. Additionally, the commenter states that, if a 
repetitive inspection interval is required, the allowed interval should 
be longer than for those airplanes on which corrosion is found. The 
commenter suggests that existing inspection results be used to specify 
longer intervals for remaining airplanes on which no corrosion is 
found.
    The FAA does not concur with the commenter's request. Corrosion has 
been found to develop in the top and bottom shear decks of the left and 
right stub wings in the area of the forward pintle pin of the MLG due 
to migration of the retaining pin following the loss of the retaining 
circlip. A single inspection of this area would be inadequate to detect 
corrosion that could develop if the circlip is lost at a later time. 
Further, in developing the repetitive inspection interval, the FAA 
reviewed the available data regarding the existing circlip design and 
considered the recommendations of the Civil Aviation Authority (CAA), 
which is the airworthiness authority of the United Kingdom, and the 
manufacturer. Therefore, the FAA has determined that repetitive 
inspections are necessary at the specified intervals in order to 
adequately address the identified unsafe condition, unless terminating 
action is accomplished.
    However, as provided for in paragraph (b) of this AD, operators may 
elect to accomplish removal of corrosion and installation of bushings, 
which would terminate the requirement for repetitive inspections. 
Additionally, the FAA has reviewed Shorts Service Bulletin SD360-32-35, 
dated September 1996, which describes procedures for installation of a 
pin and nut in lieu of the retaining pin and circlip, and determined 
that, for Model SD3-60 series airplanes, accomplishment of this 
modification also is acceptable for terminating the repetitive 
inspection requirements of this AD. Accordingly, this provision has 
been added as a new paragraph (c) of the final rule.

Tracking of Inspections for Wear

    The same commenter requests that the proposed inspection of the pin 
and shear decks for wear be tracked separately from the inspection for 
corrosion of the shear decks. The commenter notes that wear will occur 
as a function of gear cycles, not calendar time, and is expected to 
occur only if the circlip is missing. The commenter points out that the 
AD requires operators to perform the wear inspection even if an 
airplane has not flown during the 6-month interval between inspections. 
The commenter suggests that the inspection for wear should be tracked 
as a function of flight cycles, and if no wear is found during the 
initial inspection, the repetitive inspection interval for that 
inspection should be extended.
    The FAA does not concur that the two inspections should be 
separately tracked. Although wear of the top and bottom shear decks of 
the left and right stub wings in the area of the forward pintle pin of 
the MLG is expected to occur as a function of flight cycles, the 
inspection for corrosion in this area must be accomplished at intervals 
not to exceed six months. Since access to the same area is required to 
accomplish both inspections, it is considered most cost effective for 
operators to accomplish both inspections at the same time. However, if 
operators wish to perform these inspections as two separate maintenance 
actions, requests may be submitted under the provisions of paragraph 
(d) of the final rule. The

[[Page 12248]]

FAA may approve requests for such an adjustment of the compliance time 
if data are submitted to substantiate that such an adjustment would 
provide an acceptable level of safety.

Manufacturer Repair Approvals

    The same commenter requests that the proposed AD be revised to 
allow repairs to be used if they have been approved by Shorts, rather 
than requiring operators to request repair approvals through the 
Manager, International Branch, ANM-116, FAA, Transport Airplane 
Directorate, as specified in paragraph (a)(3)(ii)(B) of the AD. The 
commenter states that, from previous experience, the ANM-116 Branch 
Manager will require a Shorts-approved repair if such a request is 
made. The FAA does not concur with the request to allow repair 
approvals by Short Brothers, as the FAA cannot delegate authority for 
general approval of repairs on the FAA's behalf to manufacturers. 
However, in light of the type of repair that would be required to 
address the identified unsafe condition, and in consonance with 
existing bilateral airworthiness agreement with the United Kingdom, the 
FAA has determined that, for this AD, a repair approved by either the 
FAA or the CAA of the United Kingdom (or its delegated agent) is 
acceptable for compliance with this AD. Paragraph (a)(3)(ii)(B) of the 
final rule has been revised accordingly.

Replacement of Parts

    The same commenter, also in reference to paragraph (a)(3)(ii)(B) of 
the proposed AD, states that most operators will choose to replace the 
part rather than repair it, and requests that the proposed AD be 
revised to allow replacement of the part in accordance with the 
Illustrated Parts Catalog (IPC), rather than requiring approval through 
the Manager, ANM-116. The FAA does not concur with the request to allow 
part replacement in accordance with the IPC, as the IPC is not an FAA-
approved document. However, the FAA has determined that replacement of 
the pintle pin and sleeve with new or serviceable parts is an 
acceptable method of compliance with paragraph (a)(3)(ii)(B). Paragraph 
(a)(3)(ii)(B) of the final rule has been revised to also include the 
replacement as an appropriate corrective action if accomplished in 
accordance with an FAA-or CAA-approved method.

Inspection for Presence of Circlip

    One commenter suggests that the proposed AD be revised to include 
an inspection for the presence of the circlip, since it is the loss of 
the circlip that causes the wear and corrosion to occur. The commenter 
also recommends that this additional inspection be required to be 
accomplished immediately, prior to the proposed inspection threshold of 
90 days, if the presence of the circlip can be easily determined.
    The FAA does not concur. Short Brothers Service Bulletins SD360-53-
42, dated September 1996, and SD3-60 SHERPA-53-3, dated November 4, 
1997 (which are referenced in the AD as the appropriate source of 
service information for accomplishment of the inspections for wear and 
corrosion), describe procedures for installation of a circlip if the 
part is not in position at the time of the inspection. Although an 
inspection for the presence of the circlip is not specifically 
described, the inspection procedures will ensure that the circlip is in 
place following accomplishment of the initial inspection. Additionally, 
in considering the compliance time of 90 days for the inspection, the 
FAA cannot conclude that a reduction of the proposed compliance time, 
without prior notice and opportunity for public comment, is warranted. 
In developing an appropriate compliance time, the FAA considered the 
safety implications, the manufacturer's recommendations, the average 
utilization rate of the affected fleet, and the practical aspects of an 
orderly inspection of the fleet during regular maintenance periods. No 
change to the final rule is necessary in this regard.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    The FAA estimates that 58 Model SD3-60 series airplanes and 28 
Model SD3-60 SHERPA series airplanes of U.S. registry will be affected 
by this AD, that it will take approximately 13 work hours per airplane 
to accomplish the required actions, and that the average labor rate is 
$60 per work hour. Based on these figures, the cost impact of the AD on 
U.S. operators is estimated to be $67,080, or $780 per airplane, per 
inspection cycle.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the requirements of this AD 
action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

99-06-07  Short Brothers PLC: Amendment 39-11071. Docket 97-NM-106-
AD.

    Applicability: All Model SD3-60 and SD3-60 SHERPA series 
airplanes, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For

[[Page 12249]]

airplanes that have been modified, altered, or repaired so that the 
performance of the requirements of this AD is affected, the owner/
operator must request approval for an alternative method of 
compliance in accordance with paragraph (d) of this AD. The request 
should include an assessment of the effect of the modification, 
alteration, or repair on the unsafe condition addressed by this AD; 
and, if the unsafe condition has not been eliminated, the request 
should include specific proposed actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct corrosion and/or wear of the top and 
bottom shear decks of the left and right stub wings in the area of 
the forward pintle pin of the main landing gear (MLG), which could 
result in failure of the MLG to extend or retract, accomplish the 
following:
    (a) Within 90 days after the effective date of this AD, conduct 
an inspection for corrosion of the top and bottom shear decks of the 
left and right stub wings in the area of the forward pintle pin of 
the MLG, and measure the retaining pin holes of the pintle pin for 
wear; in accordance with Part A. of the Accomplishment Instructions 
of Short Brothers Service Bulletin SD360-53-42, dated September 1996 
(for Model SD3-60 series airplanes), or Short Brothers Service 
Bulletin SD3-60 SHERPA-53-3, dated November 4, 1997 (for Model SD3-
60 SHERPA series airplanes), as applicable.
    (1) If no corrosion, wear, or discrepancy of the measurement of 
the holes for the retaining pin of the pintle pin is found, repeat 
the inspection required by paragraph (a) of this AD thereafter at 
intervals not to exceed 6 months.
    (2) If any corrosion, wear, or measurement of the holes for the 
retaining pin of the pintle pin is found that is within the limits 
specified in Part A. of the Accomplishment Instructions of the 
applicable service bulletin, prior to further flight, repair the 
discrepancy in accordance with the applicable service bulletin. 
Thereafter, repeat the inspection required by paragraph (a) of this 
AD at intervals not to exceed 6 months.
    (3) If any corrosion, wear, or measurement of the holes for the 
retaining pin of the pintle pin is found that is beyond the limits 
specified in Part A. of the Accomplishment Instructions of the 
applicable service bulletin, prior to further flight, perform the 
actions required by paragraph (a)(3)(i) and (a)(3)(ii) of this AD.
    (i) Remove the corrosion and install bushings on the upper and 
lower shear webs in the retaining pin holes for the pintle pin in 
accordance with Part B. (left MLG) and/or Part C. (right MLG), as 
applicable, of the Accomplishment Instructions of the applicable 
service bulletin.
    (ii) Perform a visual inspection of the pintle pin and the 
sleeve for any discrepancy, in accordance with Part B. and/or Part 
C., as applicable, of the Accomplishment Instructions of the 
applicable service bulletin.
    (A) If no discrepancy is detected, the pintle pin and the sleeve 
of the pintle pin may be returned to service.
    (B) If any discrepancy of the pintle pin and sleeve is detected, 
prior to further flight, repair the pintle pin and sleeve or replace 
the pintle pin and sleeve with new or serviceable parts, in 
accordance with a method approved by either the Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
or the Civil Aviation Authority (CAA) (or its delegated agent).
    (b) Removal of corrosion and installation of bushings in 
accordance with Part B. and/or Part C., as applicable, of the 
Accomplishment Instructions of Short Brothers Service Bulletin 
SD360-53-42, dated September 1996 (for Model SD3-60 series 
airplanes), or Short Brothers Service Bulletin SD3-60 HERPA-53-3, 
dated November 4, 1997 (for Model SD3-60 SHERPA series airplanes), 
as applicable, constitutes terminating action for the repetitive 
inspection requirements of this AD.
    (c) For Model SD3-60 series airplanes: Replacement of the pin 
and circlip with a new pin and nut in accordance with Short Brothers 
Service Bulletin SD360-32-35, dated September 1996, constitutes 
terminating action for the repetitive inspection requirements of 
this AD.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, International Branch, ANM-116. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, International Branch, ANM-116.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (f) Except as provided by paragraphs (a)(3)(ii)(B) and (c) of 
this AD, the actions shall be done in accordance with Short Brothers 
Service Bulletin SD360-53-42, dated September 1996, and Short 
Brothers Service Bulletin SD3-60 SHERPA-53-3, dated November 4, 
1997. This incorporation by reference was approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Short Brothers, Airworthiness & 
Engineering Quality, P. O. Box 241, Airport Road, Belfast BT3 9DZ, 
Northern Ireland. Copies may be inspected at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 
at the Office of the Federal Register, 800 North Capitol Street, 
NW., suite 700,Washington, DC.

    Note 3: The subject of this AD is addressed in British 
airworthiness directives 005-09-96 and 005-11-97.

    (g) This amendment becomes effective on April 16, 1999.

    Issued in Renton, Washington, on March 4, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-5991 Filed 3-11-99; 8:45 am]
BILLING CODE 4910-13-P